


Sirens Among Us

by mako_and_tails_and_stuff (ElfWhoLikesCookies)



Series: Mako Unseen : A Collection of One-Shots [13]
Category: Mako Mermaids, Siren (TV 2018)
Genre: Blood and Injury, F/F, F/M, Gen, Gore, Siren typical violence/language, Violence, siren!au, siren!character, siren!lore
Language: English
Status: In-Progress
Published: 2020-10-27
Updated: 2021-01-04
Packaged: 2021-03-09 05:40:04
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 12,709
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27229717
Author URL: https://archiveofourown.org/users/ElfWhoLikesCookies/pseuds/mako_and_tails_and_stuff
Summary: Something’s happening out at Mako. There’s a new predator on the hunt, each Full Moon is bringing a higher danger. And that's without what's happening with Carly.
Relationships: Cam Mitchell/Carly Morgan, Rita Santos/Veridia (background), Zac Blakely/Evie McLaren (background)
Series: Mako Unseen : A Collection of One-Shots [13]
Series URL: https://archiveofourown.org/series/1113549
Comments: 2
Kudos: 9





	1. Chapter 1

**Author's Note:**

> Sirens Among Us: Mako Mermaids x Siren Crossover
> 
> This was a request from Twilightroxas7

_ What a life _ . Ondina thought it every morning. This morning in particular. Standing with Veridia on the north shore of Mako before the sun had even risen looking at a decapitated shark’s head. 

“This is the third month in a row,” Ondina nudged the shark’s head with her toe.

“Ondina,” Veridia chastised.

“What? It’s dead, not like it’s gonna bite me.” All her life she’d wanted to be a part of the Council, now she finally got her place and this was what she was doing - looking at dead sharks. And dead dolphins. Even a dead whale. 

Ondina’s phone buzzed in her pocket. She fished it out and answered it without bothering to check who it was.

“Yeah?”

“Is Veridia with you?” Rita asked through the speaker. 

“Why? She skip out on you this morning?”

“There’s another one,” Rita said, completely ignoring what Ondina said. “A dolphin, torn to pieces on the beach. The Marine Park took the body in.”

Great. Now land people were involved. 

“There’s a tiger shark here. Well the head of a Tiger shark. Not sure where the rest of it is.” Ondina shifted her phone and covered the microphone. “It’s Rita. She said there was a dolphin found on the beach all torn up.”

“Like those two from last month,” Veridia said. 

“Keep an eye out for anymore,” Rita said over the speaker. 

“I will. There’s a tiger shark body to find,” Ondina hung up and re-pocketed her phone. 

**_Two Months Ago_ **

“What is up with all these fish?” Ondina looked to Mimmi, checking the other Mermaid was looking at the same scene as she was. Fish parts lay scattered the whole stretch of the coast. Mostly tails, but the occasional head had stared blankly at the pair as they stood upon Mako’s north shore.

“I have no idea.”

“Come on, we need to see how far up these go,” Ondina lead the way along the beach. 

As it turned out - they went far. 

“Looks like someone was really hungry last night,” Ondina remarked as she sidestepped another fish. There were so many. Some were pretty big fish too. She had a big appetite, but even she couldn’t eat anywhere close to this amount. 

“There’s no way one Mermaid could eat so much,” Mimmi said, “not even Zac could eat this much and he never stops eating.”

“They’re not all eaten - look,” Ondina pointed to a mostly intact mackerel. The large fish had a single bite torn out of it’s stomach and it wasn’t the only one in sight. “There’s about four more ahead of us the same, then it looks like that’s it.”

“No Mermaid would leave so much waste lying around,” Mimmi said, “stuff like this draws attention.” 

It was true. Land people noticed dead things. Every whale that washed up on the beach drew crowds of land people desperate to catch a glimpse. Something like this with at least a hundred, easily more, fish lying half eaten - it would draw masses or normal spectators and scientists. 

“As long as it’s just on Mako we’ll be fine,” Ondina said. 

“You still need to tell the Council.”

Ondina groaned, “fine.” It wasn’t as simple as just telling the council. Unless she managed to catch Veridia directly, she’d have to find Aitne and tell her, who would then gather the lower Council so they could be informed, then Aquata would take it to the Higher Council. 

The other shortcut would be to tell Rita and get her to pass it onto Veridia. 

“It’s not what you thought it would be is it? Being on the Council?” Mimmi asked. 

“You can say that again.”

Evie pulled out her phone and checked the time - twenty eight minutes past seven. Two minutes until the Ocean Cafe opened for the day. Right now it was empty save for David bustling about getting ready for opening, herself, and Zac who was eating a bowl of prawns under the guise of pretending to help her set up her shop for the day.

There was one very important person missing that no one else had commented on.

“Have you guys seen Carly?” Evie asked. It wasn’t like Carly to not be here by now. 

“Nope,” Zac popped the ‘p’ and dropped another prawn in his mouth. 

“She should be here by now,” Evie mused, “she’s never late.” 

Carly was the type who showed up fifteen minutes or more before her shift started, a lesson people like Erik and Ondina could really do with learning, but today with her shift now a minute away from starting - there was no sign of Carly. 

“Maybe she’s just running late?” Zac spoke through a full mouth of prawn meat. 

“Carly doesn’t do late,” David backed up Evie’s thinking. “Have you messaged her?”

“Doing it now,” Evie opened her text messages and typed out a message to Carly before pressing send. No sooner had she pressed send, her phone buzzed to life in her hand. Evie swiped up the answer without stopping to check who it was. Her automatic assumption was that it was Carly, calling to explain that she’d slept in or that she got stalked by a pelican or something. 

“Hey!” 

“Hi Evie.” That was not Carly’s voice. 

“Mrs Morgan, hi.” 

Both Zac and David’s heads snapped in Evie’s direction when they heard who she was talking to. 

“I’m sorry for bothering you so early but is Carly there with you? She never came home last night and I know she’s supposed to be working this morning. I’ve called Cam as well but he hasn’t seen her.”

Evie’s stomach sank. This was now three times in the last three months she’d had Carly’s mum phoning asking where Carly is. 

“She’s not arrived yet,” Evie answered truthfully.

“If she does will you get her to phone me?” Mrs Morgan asked. “If she’s not here soon we’ll have to contact the police.”

“Of course Mrs Morgan.”

“Thank you Evie.” 

Carly’s mum ended the call and Evie slowly set her phone down on her counter.

“I heard the word police, what’s going on?” Zac asked.

“Carly’s mum said she never came home last night. Again.”

“She left here after closing,” David said, “haven’t heard from her since.”

“Do you think something happened?” Zac asked. “I mean, I don’t know if you’ve noticed but it’s always after the Full Moon this happens.”

“I don’t want to think about that,” Evie said. Full Moons were unpredictable, even for land people. Wasn’t it an old wives tale that Full Moons made people go crazy. “It’s not like Carly not to go home but this is the third time this has happened.”

“And after a Full Moon,” Zac reiterated. 

“Have you asked Cam?” David asked, weaving between tables over to Evie’s counter.

“Her mum phoned him too. He said she wasn’t with him.”

“What about the Mermaids? Have they seen her?” 

The Mermaids always seemed to know something. Especially the little ones - too many of them hung out too close to land, seeing everything. She blamed Ondina. The little ones were all behaving, staying close to Mako and then Ondina covered Rita’s classes for a week and all of a sudden Evie was seeing little fins everywhere. 

“Haven’t seen them this morning,” Evie said. “It’s too early for them to be up.”

“Mimmi said last night she had to check the coast for any remains again,” Zac shoved his now empty bowl away from him. 

“Remains?” David asked, eyebrows furrowed. 

“The last two Full Moons, the morning after, there's been all these sea creatures found all ripped up, mostly around Mako but there’s a couple further up the coast,” Zac explained. 

It was all the Mermaids were talking about, and all Ondina complained about - being roped into searching for dead animals when she could be sleeping. 

“So what’s doing it?” David asked. “A shark?”

“I said that,” Evie answered. It had been her first suggestion that first morning. “But Ondina said if it was a shark there would be less parts found. A hungry shark would eat more of the animal than whatever’s attacked these creatures.”

“Maybe it’s sick?” Zac suggested with a slight shrug. “Like in Hemlock Grove - how the werewolf wasn’t eating what it killed cause it was sick.”

“Unlikely Zac,” Evie said. She highly doubted a Pod of over a hundred Mermaids would be able to miss an ill shark going around attacking things. And as Zac kept saying - it was always after a Full Moon. Sharks don’t only hunt on Full Moons. 

“Maybe it’s a werewolf and it’s attacking along the coast, getting whatever comes close?” David suggested. Evie almost rolled her eyes. “What type of things are being attacked?”

“Mostly fish but there’s been a couple dolphins too,” Zac answered then turned his attention to David. “Wouldn’t a werewolf eat as much as it could though?”

“Not if it’s a vargulf,” David pointed out. 

Evie sighed. Those two were too much into the horror side of things. And that was without Cam adding to the mix. Sure she enjoyed the odd episode of the Vampire Diaries, but she only watched it for Carly’s sake. Carly who was still not here. 

“True,” Zac pointed his index finger. 

“It’s not a werewolf,” Evie finalised the discussion, they had more pressing matters than Werewolves of Vargulfs. “Werewolves don’t exist.” 

Then she had a thought, “Do they?” 

“You know, the Mermaids have said,” Zac said, “we’ll ask later.”

“We need to ask them about Carly first,” David said. 

“I’ll phone Ondina now,” Evie picked her phone back up and found Ondina’s contact. The lack of a new message from Carly was really getting to her. 

Carly woke in a state of pure confusion.

The rock bit into her arm and the sand beneath her skin scratched and tore at her like millions of tiny needles. She couldn’t feel to move. She couldn’t think to move. Her legs were stiff and heavy, attached to her body like a deadweight and her arms were no better. She could feel warm blood dripping from where the rock was pressing into her arm. She needed to move her arm. Why couldn’t she move her arm?

The drumming of the waves echoed around her skull, pounding and thudding with every movement she managed to make. She pulled her arm carefully away from the rock, hissing as a spurt of blood accompanied the action. She dropped her arm on to the sand with a soft thud. Red spots dripped onto yellow. 

She had to get up and start to put together how the hell she ended up on an unfamiliar beach, cold, wet, and missing her clothes. Sure she liked a swim but even she knew better than to go out skinny dipping alone at night. Then she had to figure out how to get home, preferably without getting arrested for public indecency. 

Carly couldn’t recognise the low cliff face off to the left or the sprawling beach to the right. She didn’t know if this was a public beach that people used or one far from anything. From where she was, lying amongst the rocks, someone could be only a few steps away from her and she’d never know until it was too late and they’d seen her. 

Sighing heavily Carly struggled to her feet. She was so stiff.

What the hell happened last night? 

“Anything yet?” David paused at Evie’s shop on his way back to the kitchen, his tray laden with glasses. Three hours into the shift and still no Carly. Evie had phoned Ondina with no response, same as Mimmi. The only Mermaid who actually answered was Rita who hadn’t seen Carly or any of the other Mermaids, but had spoken to Ondina. 

Evie shook her head, “no texts, no calls. Her mum phoned again - they’ve filed a missing persons report.” 

“Someone has to have seen her,” David said, “people don’t just disappear.” 

“They do around here.”

He didn’t want to admit it but Evie was right. People went missing all the time. Not all of them were found. 

Taking one last glance over the typed report that had been shoved into his hands Doctor Mitchell Ross, or ‘Mitch’ to most people save his mother, turned it away and opened the door to the lab where the torn up dolphin lay. 

His report was a mess. It made no sense. Whatever attacked that poor creature was not something he could say. In all his years he’d never seen anything quite like this. Picking the paper up again he looked over the typed garble before tossing it onto the work table. 

Doctor Ross turned his attention back to the dolphin on the metal table. A woman with dark red hair braided back stood at the table, looking over the creature. He’d called her after he’d finished his initial examination of the dolphin - who better to help than a Mermaid?

“Did anyone see you come in?” He asked. If anyone had seen her it would be his position on the line, very few employees were even allowed done here, let alone someone with no professional affiliation to the marine park or marine biology. To be completely fair she probably knew more than the vast majority of his employees. Not that his superiors would see it that way. 

“No, no one saw me,” Rita replied, not taking her eyes off the dolphin in front of her. If he didn’t know her, it would be easy enough to mistake her attitude as dismissive, but there was worry there. 

“Good,” Dr Ross nodded. 

“What do you think?” Rita asked, turning to face him. 

“There is a substantial amount of damage,” he replied. “Whatever attacked it tore right through to the bone. I found teeth marks on some bones from some kind of sharp toothed animal.”

“What would you say attacked it?” Rita asked. 

His immediate thought had been shark or maybe orca but it didn’t feel right. 

“That’s where I was hoping you would help. The bite pattern looks like it could be a match that of some kind of shark or Orca even but … “

“The bite radius is too small” Rita finished his sentence. 

“Exactly. The bites are almost … the only thing coming to mind is a seal, but the teeth are wrong for a seal and honestly it’s too big.” 

It was starting to annoy him what it could be. Everything small enough had the wrong teeth. The teeth that matched, had a bite radius that was too large. 

“Are there any clear bites?” 

“A few,” Dr Ross moved round to the other side of the dolphin, “the clearest is right here.” He lifted the flipper, hanging on by a string. A chunk of flesh was torn away from the side in a neat crescent moon of peirce marks. 

“What would you say caused this?” Dr Ross asked. Rita was a Mermaid after all, surely she’d have more of an idea than him. 

“Honestly, I’d say a Mermaid did this. The bite mark is too human to be anything else.”

That was the last thing anyone needed, a Mermaid going around attacking animals. How long before they turned on a human.

“I didn’t think Mermaids had sharp teeth,” he said. You learn something new everyday. 

“We don’t normally, but there are … individuals.”

“I’m not sure I like the sound of that…”

“I don’t either,” Rita said. “There’s someone I need to talk to but thank you for your help. I’ll keep you updated if I hear anything.”

“I’ll let you know if anything develops at this side.”

“Thanks.”

“What are you going to put in your report?”

“The one I’ve already done lists the species as unknown.”

“Say it was a shark, a juvenile shark. It should cover it.”

“Thank you.”

“Do you really think a Mermaid attacked it?” Dr Ross asked.

“I’m not sure.”

The walk along the beach was long. Long, tiresome and so, so long. Carly lost track of how far she’d gone, but the cliffs she’d first seen when she woke up were nothing but specks in the distance. 

She’d grabbed a towel that she’d found folded neatly on some rocks. It seemed clean enough, apart from the sand but in her state any cover would have been gratefully received. Actual clothes would have been nicer but she wasn’t going to complain. 

She would complain about the long walk along the shore. The slow progress as her feet sunk deep into the soft sand and hindered her progress. She didn’t even know if she was going to right way, she only started off this way because the cliffs cut off the curve of the coast the other way. 

The first thing that hit Mimmi when she surfaced in the shallows was the ringing. Something was making an awful ringing nose. A quick scan around revealed no obvious source. Mimmi ducked under the water and swam the two lengths to shore and dragging herself up the wet sand. 

The ringing was louder now. 

Mimmi dried herself off and focused her eyes on the sand. Things don’t ring for no reason. 

With each step she walked closer to the Ocean Cafe dock, the louder it got.

Then she saw it. A pair of dark blue shorts, a ringing phone in the pocket, the screen lit up through the fabric. A red shirt was thrown beside it and a single white trainer upside down on top of the shirt. 

Mimmi slipped the phone from the pocket and the ringing stopped.  _ 15 Missed Calls from Mum. 13 Missed Calls from Evie.  _

Evie? 

Mimmi gripped the phone tighter and jogged along the sand until she could climb up onto the dock. Mimmi clambered up onto a rock and pulled herself up onto the wooden dock behind the cafe, she slipped around the front, no one noticing her appearance and hurriedly crossed the dock into the cafe.

She saw Evie straight away, anxiously looking at her phone. Mimmi shot over to her.

“Mimmi! I was trying to reach you earlier but … where did you get that?” Evie trailed off and her eyes caught what Mimmi held in her hand. Mimmi held the phone out. 

“I found it under the dock with a pile of clothes.”

“It’s Carly’s.” Evie said, turning the phone on and looking it over. “No one’s seen her since last night. Was there anything else?”

“Clothes and shoes. That’s it.” Carly was missing again. No wonder Evie was so worried. 

“What about footprints?”

The sand had been clear of anything like that. The tide would have gotten to anything that was there

“Didn’t see any but this had to have been left after high tide or the Sea would have taken it. The tide’s coming back in now so anything else will have been washed away.” 

“Show me.”


	2. Chapter 2

The expanse of beach slowly meandered its way around another curve. By now Carly could hardly lift her feet and her mouth was drier than the sand beneath her. 

Then finally she saw it. The first recognisable landmark. Mako Island. The island lurked behind a roll of cloud over the sea, no doubt from some little Mermaids practising their Powers. This was not the weather for low clouds to be there themselves. Which would mean it was the north side she was looking onto. The Mermaids only practised out in the open on the north shore. 

So she was heading south. Back down  _ towards _ the Gold Coast. Back towards home. She was going the right way. The flash of hope renewed her spirit and she set onwards picking her feet up and lifting her head. 

\------------------------------

Mimmi was right.

Evie had hoped beyond hope that Mimmi was wrong. That there was some trace left. Some footprint. Some scuff in the sand. Anything. 

But Mimmi had been right. 

Anything that was there was gone now, the tides taken it away and spread it across the ocean. 

Evie scooped up Carly’s shirt and shorts. The shorts dropped from her grasp as she took in the state of Carly’s shirt. The entire back of her shirt was torn. Deep rips across the shoulders and up both sides like something had grabbed her. 

“Mimmi,” Evie held the shirt up. Worry pooled in her stomach. Nothing about this situation was good, but this was the rotten cherry on a melted ice cream. 

“Let me see,” Mimmi held out her hand. Evie handed the ruined fabric over and once again picked up the shorts and gave them a check over. As far as she could see they had not suffered the same damage as the shirt. 

The worry eased only slightly. 

“I have never seen marks like these before but those are some serious claws,” Mimmi announced. 

“Claws?” Evie did not like the thoughts that flooded her head with. Zac and David’s earlier spitballing of ‘werewolf’ started to look more likely. 

“All I think of is a crocodile but they tend to go for teeth, not claws. And there’s no blood. It’s more likely something found this and ripped it up.”

Was that comforting? Not really. Not really. Carly was still missing. Her clothes were still on the beach and they still had no idea what happened. 

“It still doesn’t explain why her clothes and phone are here and she’s not,” Evie was on the verge of snapping. Mimmi didn’t deserve it. 

“If she was a Mermaid I’d say she took off in the water.”

Really Mimmi? Carly was most definitely a land girl. It was a pretty established fact. 

“But she’s not,” Evie pointed out. 

“It’s worth a look,” Mimmi shrugged. “I’ll head out from here, the main current goes north - if she went in the water she’s probably gone north. I’ll follow the coast up and see if I find anything.”

“I’m coming with you.” 

“What about the shop?” Mimmi asked. It was an innocent enough question but there are more important things right now than her shop. 

“Carly’s more important. Let’s go,” Evie kept Carly’s shorts clutched in her hand and easily crossed the short bar of sand, diving into the water, Mimmi on her heels. 

\-----

With every slowing step Mako grew larger. 

One.

Little.

Fraction.

At.

A.

Time.

Carly took another deep breath and tried to reinstill some of that hope from earlier. It faltered with her step. The sand rose up to her and only slightly cushioned the impact of her hitting the ground. 

\----

Evie followed Mimmi to the surface. The ocean had zipped past in a bubbled blur as Evie stuck close behind Mimmi all the way up the coast. According to Mimmi there was a currant this way but Evie felt nothing, just plain ocean. Still Mimmi had lived here all her life and knew the waters. Who better to trust about the ocean than a Mermaid? 

Evie broke the surface and took a breath, relishing the fresh oxygen in her lungs. She’d never come this far up before, Mako was just a speck to the south and the shore was unrecognisable. 

“Where are we?” Evie asked.

“North.”

Useful. Being out in the middle of the ocean was not helping. Carly could swim but to be out here? That was beyond even the strongest of human swimmers. 

“If we head closer to the shore and swim back south we can keep surfacing and if there’s anything we’ll see it.”

“I guess.” 

\----

Carly stayed down where she fell, letting the warm sand comfort her as she rested her feet. Just for a little bit. Then she’d get up again. 

By now her parents would have noticed she was gone and she had no way of letting anyone know she was okay. She had to get up and get back home. She had to.

Once again struggling upwards, Carly got to her feet. She re-adjusted her towel from where it had slipped down when she fell and set out once more. She wanted to be home more than anything.

\-----

They set up a pattern. Surface. Check the beach. Submerge. Swim. Surface. Check. Submerge. Swim. Surface. Check. 

The beach passed quickly with no sign of Carly. Or anyone at all. Evie let Mimmi set the pace until she worked out the timings in her head and took the lead. 

Evie surfaced for easily the hundredth time to a beach with nothing. She buried her face in her hands and the thought of just slipping below the water and giving up crossed her mind. If the police couldn’t find people, couldn’t find Carly, how could two Mermaids?

“Evie, is that her?” Mimmi asked.

Evie lifted her head. A blonde girl was walking along the beach. All the rocks must have hidden her from view. 

She was dragging her feet and hanging her head but that walk - it was Carly’s walk. It had to be. It had to be Carly. 

“I think it is!” 

Evie dove back under, slapping her fin against the surface as she shot forward, speeding towards the shore. She didn’t slow even as the sand sloped up and the water grew shallow. She only slowed once she hit the sand, all but throwing herself up onto the shore. 

Evie quickly dragged herself clear of the waves as Mimmi appeared in front of her in the shallows and began the same process. Drying faster than she ever thought possible Evie leapt to her feet and ran up the sand. 

The blonde girl’s head shot up. That face. She knew that face. 

“Carly!” 

\---------------------------

Carly thought she was hallucinating. She was tired. She was dehydrated. She was not good. She saw the lines in the water but shook it off as her eyes playing tricks. The same with whatever she thought she saw moving behind a clump of rocks. And the same when she saw Evie come running up the beach from nowhere. 

“Carly!”

“Evie?” Carly blinked. Evie stayed in her vision, running up to her. She was here. She was really here. 

“Where have you been?” Evie threw her arms around her and Carly collapsed forwards into her. She was saved. Someone was here to help and get her away from this nightmare. 

“I have no idea,” Carly admitted. 

\---------------

Carly stared at the shower box trying to decide which button to press or dial to turn to get the shower to stop. Mimmi had turned it on and forgotten to tell her how to turn it off. Carly wiped the water away from her eyes and gave up, getting out the shower leaving the water running. 

The pull switch with the silver seahorse handle stopped the water. Her mum always told her it was bad to turn the shower off that way, if it had been any other day she’d feel bad about possibly damaging someone else’s shower but today everything was too much of a mess to think too much into it. 

Drying quickly Carly pulled on the fleecy pjs Mimmi had leant her and twirled the towel around her hair. Her phone lay on the sink taunting her with dozens of unread messages and missed calls. She couldn’t keep ignoring them - it wasn’t fair on her parents. The whole way back she’d been desperate to let them know she was okay but now that it was time - different story. 

Carly forced herself to pick up her phone and called her mum. Her mum answered on the second ring. 

“Where the hell have you been Carly? Do you have any idea how worried we were? You can’t just disappear like that - especially not after the last couple months.”

That brought back memories. 

\------ 

**Two Months Ago**

Carly slipped in the door and shut it behind her as quiet as humanly possible. Still not quiet enough from her mum’s bat like hearing. The moment the door clicked her mum appeared from the lounge and descended upon her, smothering her in a hug. Her dad right behind her, but remained lurking at the door frame. 

“Where the hell have you been Carly?” Her mum broke away but kept her hands on Carly’s shoulders, looking her up and down. 

“I was ... at Evie’s,” Carly lied. 

Really she had no clue where she’d been, she’d woken up on the beach without any clothes and zero memory of the night before. The only upside was that in whatever possessed state she had been in to get herself in that position was smart enough to leave her in one of the secluded coves the Mermaids used. One of the secluded coves where the Mermaids stashed spare clothes for any newbie Mermaids to come to land and one where they’d all gone swimming a couple of times since the Pod came back. 

“No you weren’t because I called Doug and asked him.”

Fuck.

“Turns out Evie was staying with whatever her name is - Mima or something and got home two hours ago,” Mrs Morgan said. “So where were you?”

“I stayed at Cam’s,” Carly lied again. She never lied to people. Now two lies in less than two minutes and to her mum of all people. She didn’t want to unnecessarily worry anyone so thought it best to keep her mouth shut about the reality of last night. Especially when she didn’t have the truth to tell. 

“Carly Morgan I have told you before about staying out without saying anything.”

“I know, I’m sorry. It won’t happen again,” Carly promised. 

That had been a lie. The next Full Moon her parents had been the ones who found her on the beach further down the coast this time, closer to come.

\---------------------------------

“I’m really sorry mum,” Carly apologised. She really didn’t mean for it to happen again but something seriously fucked up was happening to her and she didn’t know what. “I was out helping David and the boat died and my phone died and David didn’t have his and -”

“Where are you?” Her mother interrupted Carly’s long winded and complicated excuse. 

“At Principal Santos’. Her niece helped get us back to shore and it was closer than home to get my phone charged to call you.”

“I’m coming to get you. Stay there.”

Her mum hung up before she could get another word out. 

Carly sighed, gathered her old clothing and made her way back through the house, praying she wouldn’t get lost. 

\--------------

She got lost. Mimmi had to come and find her and lead her to the kitchen where Evie greeted them with three mugs of tea. 

“What happened?” Evie asked softly. 

Carly took a sip of the tea Evie had made her, letting the warm flow over her tongue and down her throat, warming her up inside, “I woke up on the beach with no idea how I got there. No clothes or anything.”

“We found your stuff under the dock at the cafe,” Mimmi said.

Back on the beach Evie had given Carly her shorts that had been warmed and dried, then soaked through again as the two Mermaids helped her swim back down the coast. The shorts stuck to her legs while the top Mimmi had lent her had billowed and flowed under the water. No mention of her own top though. 

Thankfully once arriving at Rita’s house Mimmi had dried her off, let her use the shower and then given her a pair of really, really warm fleece pajamas - dark blue ones with rainbows all over them. 

“I don’t remember being there.” She never went under that dock. As far as docks went - it wasn’t a nice one to be under let alone get undressed under and apparently go swimming from. 

“What do you remember?” Evie asked, holding her own cup of tea. 

“Leaving the cafe. That’s all.” 

She wished she knew. It was the same last month. And the month before that. Every month since that thing attacked her. 

\------------------

**Three Months Ago**

Carly jogged down the dock, balancing the large stack of boxes in her arms to where David was waiting in his boat. By now the sun had set, the rays that graced the sky all day were now gone. The Moon had taken it’s place, the silver light catching on the waves. 

She blamed Erik. He took off after everything that happened, once again leaving them short on help. Usually Evie would help out but tonight was the Full Moon and Evie was off out with the Mermaids. So Carly was left helping David load up his deliveries to drop off on his way home. 

Least he paid her overtime. She was supposed to have been home by now for a relaxing Tuesday night in. 

“Is that it all?” 

“Finally,” David replied, “Thanks Carly. See you tomorrow.” 

“Bye David.”

David started the boat’s motor and set out across the dark water. If his parents knew how often he went out after dark on the boat doing deliveries - they’d take his boat away. 

Carly sighed and made her way back towards the land. She should really get a moped or something, the thought of walking all the way home was not a happy one. 

Something splashed to the side of her. Carly followed the noise with her eyes but saw nothing. Probably just a Mermaid. The little ones were becoming out of control and on a Full Moon with everyone else celebrating? It was a riot. 

Shaking her head Carly continued on down the dock.  _ Mermaids.  _

A sharp splash sounded again, closer in this time. 

She hardly had time to turn to investigate the noise before something lunged from the water and crashed into her. Carly was knocked to the side, slamming hard into the wooden dock, the air forced from her lungs and would not return to her. 

There was something on top of her. Wriggling and shrieking. 

Carly twisted round, a silent scream catching on her lips as whatever it was sliced her arm open. She shoved the thing off her. It’s skin was cold and wet under her touch. The thing hit the dock and slipped off the side with a loud splash. 

Carly lay on the dock unable to move, unable to breathe, blood leaking from her arm. 

\-----------------

“This is the third time this has happened,” Carly said. “It can’t keep happening, my parents are going insane.”

She’d never told anyone what happened to her. The wounds had closed over so fast and she had hit her head pretty hard on the dock. She hardly believed it actually happened so how was anyone else going to believe her. 

Of course this was before she started having blackouts and waking up naked on the beach. 

“Do they know you’re here?” Mimmi asked. The Mermaid’s concern was touching, Mimmi was so sweet and aside from Sirena, was the nicest of the Mermaids she’d met. 

“I phoned my mum after I showered.”

“What did you tell her?” Evie asked. 

“I told her I was helping David with deliveries, the boat got stuck, phone died and David forgot his. We were stuck until the morning and someone saw us.”

“She bought that?”

“Seemed to.” Her mum had been more relieved about knowing she was okay than picking holes in her story. For now. It might change later on. She’d have to fill David in in case her mum went interrogating him. No one deserved that, not even Ondina, and if Ondina didn’t deserve it then David most certainly did not. 


	3. Chapter 3

"How'd it go with the marine biologist?" Veridia questioned Rita the moment she set foot in the bedroom. Straight to business then. Nevermind she hadn't actually seen Veridia today, the other Mermaid had left before she woke up to help search the coasts for any evidence of more dead creatures.

"He's going to write that it was a juvenile shark but he couldn't tell exactly what it was," Rita gave her the brief version. "The bites don't match anything any land people have studied."

"You know exactly what it looks like," Veridia said, turning in her seat at the dressing table to face the mirror, she pulled a shell pin out of her hair and set it down on the table. In just a few short months the entire room had gone from being 'her' space, to being very much 'their' space. At this point Veridia had more on the dressing table than Rita herself did.

"A siren." The thought was on her mind the second she saw those first fish on Mako two months ago. As Dr Ross had kept saying about the bites - they were all wrong for anything else. Human sized bites with shark like teeth? It screamed 'Siren.' She hadn't wanted to buy into it; a Siren in this part of the world was not a good thing.

"There hasn't been one in this part of the world in a long time." Veridia removed another three pins from her hair, the braids they held up falling down, and set the pins beside the first one. "Can you help with these?"

Rita stood behind Veridia and began undoing the first braid, unweaving the strands, soft curls tangling around her fingers.

"There were rumours about a Siren living on land over in America." Over in Washington to be exact. There had always been high 'activity' in that area, the Pod that used to frequent the waters were often attacked by shadows. It took years before any of the Mermaids actually saw the shadow's face. Once they did - they left before the next Moon cycle began.

"Exactly. America," Veridia forced. "They don't live here anymore. If there was one living around Mako someone would have seen her by now."

Someone _would_ have seen her, nothing like that could swim by Mako without someone seeing, let alone something killing so violently.

"These attacks," Rita began, "they only happen at the Full Moon. Nothing can survive only hunting once a month. Apart from werewolves."

The irregularity of the hunting sprees had bothered her. Nothing in any Sea anywhere across the world only hunted once a month and only on a Full Moon. Nothing. There was no denying a Siren was the only real candidate for what was attacking those poor creatures, but not even Sirens hunted that little.

"Don't even joke about that," Veridia twisted round in her seat. "We don't need a werewolf problem on top of a Siren problem."

Rita turned Veridia back around with one hand on each shoulder and ran her fingers through Veridia's hair, smoothing out all the curls.

"There was a werewolf here for years and he was no problem," Rita picked up a brush from the dressing table. She was 98% certain it was her brush but the hairs tangled in the bristles were unmistakably copper. Last time she checked she had dark hair. "You don't need to worry."

The Wolf was little more than a pup. He didn't bother any of them and kept himself out of trouble on the Full Moon by hiding up in the mountains. Rita had only met the boy a handful of times over the years but she felt for him.

A Wolf without a Pack is like a Mermaid without a Pod.

She emphasised with him, even with his insuffering attitude. The boy had left five Moons ago for America, before he left he promised he'd be back with a smirk and a wink. It had taken more self control than she thought she had to do nothing more than roll her eyes at him.

Rita started brushing out Veridia's hair, working out all the little tangles and knots.

"Do you remember being taught about the _troëdig_?" Veridia asked, disturbing the soft silence that had settled.

The name sounded familiar. It was Welsh. There wasn't much Welsh influence in the Mako Pod, but that name was so familiar. Then it hit her.

"Those land girls in Wales? The ones that attacked and killed those fishermen."

Three land girls, perfectly normal in every way suddenly snapped and murdered a group of fishermen along the western coast of Wales.

"The month before that they got attacked by a Siren."

That was not good news.

" _Troëdig_ means turned." Realisation hit her. "They were turned into Sirens." They were never taught that part, but then land people were turned into Mermaids, why not Sirens too? An infection passed on in the same way as lycanthropy once was.

Veridia nodded, "before that no one thought it was possible. The pod there took care of them - the next Full Moon they trapped them in a cave. Two were killed during the night when they turned on each other, and the final drowned once she changed back.

"This isn't like Zac. They don't have emotions or any sense of right or wrong. The only way to stop them is to kill them."

As much as she was loath to admit it - Veridia was right.

"We need to find out who it is first before we start thinking about any of that."

She thought it best not to mention what she found out from Mimmi earlier that day, nothing could be done until the next Full Moon, best not to aggravate things too early. After all, she knew too well what Veridia could be like.

"You already know something. I can see it on your face."

Rita met Veridia's eyes through her reflection and held her gaze before relenting.

"Carly has been disappearing every night on the Full Moon. Starting from that same Moon cycle that the Siren began hunting."

"And you said nothing?" Veridia raised an eyebrow.

"I found out seconds before coming up here. Mimmi only told me this morning after her and Evie found Carly miles up the coast with no memory of how she got there."

"She has to be dealt with."

"We have to make sure first. You are to do nothing until I make sure."

No one orders the Head of the Council around and gets away with it. No one but her anyway. She wasn't part of the Pod. She was on equal standing with Veridia as her girlfriend and Veridia listened to her.

* * *

The moment she got home Carly all but crawled into bed and collapsed, sleep instantly taking over her. The walk down the coast had drained her and the mental gap weighed heavily on her mind. She stood no chance against the siren call of a nap.

She woke up hours later only mildly better.

This whole mess had to stop before she drove herself insane thinking over everything. Carly dragged herself out of her bed, still in Mimmi's pjs and set about getting ready to face the day. Afternoon? She didn't know what time it was but as long as it wasn't stupid o'clock in the morning, she had people to see.

The thing that lay across the rock may have once been vaguely human but now? It was unrecognisable. It was not fresh dead. Anyone could see that. And smell that. The rotting flesh was bloated and torn, flies buzzing around the body and the thick trails of congealed blood.

How this was missed was beyond her. It was also a massive breach of security. If something like this could be missed - what else could be missed? These shores were supposed to have been checked this morning and this _thing_ was not a fresh kill. If she had to guess she'd say a couple months at least, on land. If it had been in the water first, then the time frame would be less.

Huge chunks of dark scale like skin were torn away from a tail of some description more akin to a dolphin's than her own. The ashen skin on the humanoid top was the same with the stomach torn open and most of the insides gone.

It looked like a Mermaid but every part of it was wrong. So wrong.

Taking a breath she ducked under the water and shot off back round the island. The Council needed to see this.

* * *

Carly rang the doorbell beside the blue door with the swirled glass and stepped back from the door to wait. Second time here today. The first time Mimmi and Evie hadn't taken her in through the underwater entrance. You really wouldn't think that looking at this house there was that place underneath it with a collection to rival Ariel's in the Little Mermaid.

She didn't have to wait long before Principal Santos opened the door. The Mermaid looked very different in her casual clothes compared to what Carly was used to seeing her in at school. Collared shirts and tight skirts replaced with a short white dress. There were even little shells pinned into her braid.

"I brought Mimmi's pajama's back," Carly held out the bag. Then stood back awkwardly once Principal Santos took the bag from her.

"Thank you," Principal Santos smiled, "I'll pass it onto her."

"Thanks," Carly slipped one hand into her front pocket. Or tried to. These shorts had fake front pockets. Her fingertips just caught on the seam.

"How are you doing?" Principal Santos asked. "I heard about this morning from Mimmi, everything okay?"

It was no surprise she knew, the Mermaids all seemed to tell each other everything. What one of them knew, they all knew.

"Yeah," Carly nodded. "Yeah it's just. It's fine, it's just fine. I should probably go."

Nothing was really 'okay' but oh well. She should really go and see David and Evie. And Cam. Someone she could actually talk to without feeling … weird.

"Why don't you come in?" Rita offered. "The kettle's just off."

"Um, okay. Thanks."

Tea sounded nice though. Her mum had made her tea but she'd fallen asleep before she could drink it and she'd been too keyed up to sit at home for another one.

* * *

"So what happened? When did this all start?" Rita set the cup in front of Carly and took a seat across from the girl.

"Three months ago. I blacked out or something and woke up the next morning in one of those caves we sometimes go swimming in."

Not a good start. Memory loss was often associated with transformations and waking up in a water filled cave? It was looking like her suspicions were confirmed already. It was too much of a coincidence for it not to be the case.

"Did anything happen before that?" Rita pressed.

"No," Carly answered too quick for that to be an honest answer. "Well…"

Nothing about that did anything to ease her worry.

"Carly, what happened?"

"It was nothing." The girl's dismissive attitude wasn't a good sign. Something happened to her and she was confident she could guess what.

"Carly."

"The last Full Moon before that I was helping David load up the boat and I got attacked by this … thing. It came from the water and knocked me over and slashed my arm."

 _Troëdig._ Land girls attacked by a Siren and turned. Carly was attacked. Carly turned. _Troëdig._

"It cut you?" Rita asked.

"Yeah, but it healed over really fast. I'm okay now."

Sirens had incredible healing, far superior to Mermaids and with less need for any of the healing salves and potions.

"Can I see?"

She'd seen her fair share of werewolf scratches over the years, she'd visited the Moon Pool in Ireland enough times to run across the Pack there. How different would Siren ones be?

"There's nothing there but okay," Carly rolled up the edge of her sleeve, "it was right across here." She drew over the rough area of the slashes. Sure enough the skin was unblemished "Healed so fast almost feels like I imagined it," Carly gave a little laugh at that.

Rita touched over where Carly marked out the cuts and the girl flinched.

"Sorry," Rita apologised. She pressed lightly against Carly's arm and moved downwards. She could feel the scars, the skin ever so slightly raised up and smoother than the rest of Carly's arm. Following the raised scar it curved around Carly's arm cutting over muscle.

"There is scar tissue there, consistent with something clawed, but healed over," Rita said. "This was four months ago now?"

"Yeah, would be," Carly confirmed, "Why did it heal so fast? What was it?"

"I'm not sure," Rita lied. Why worry the girl unnecessarily? If she told Carly, she'd spend all month worrying what was going to happen to her next time, and what the Council might do - no doubt Ondina would take full care to fill her in on exactly what the Council planned.

"I thought it was one of the little Mermaids at first but I didn't see anything. I just heard splashing and then I got knocked over by it leaping from the water," Carly pulled her sleeve back down.

"There's more out there than even a Mermaid knows."

"My parents are going insane, I can't keep doing this to them."

She felt bad for the girl, she just found out her friends were all Mermaids, and Mermen in Zac's case, and now she was pulled into that world but in such a twisted way. Mermaids and Sirens don't coexist for a reason.

"Next Full Moon why don't you stay here?" Rita proposed. If Carly was here she could be watched. Could be controlled. Then at least one of Carly's problems would be solved and the Council's problem would be solved. "If it is every Full Moon this is happening to you then staying somewhere safe is the best idea."

"What about the Full Moon celebrations?" Carly asked. "I don't want to get in the way of that."

Mermaids were inherently selfish by nature, everything came down to how to best protect themselves. It wasn't a critique, just an observation. Carly's worry of getting in the way of the Full Moon was refreshing.

"I don't celebrate with the Pod," Rita informed her, "and I'm sure Evie would stay with you if you asked."

Evie would do anything for Carly, she remembered her conversations with her after Evie first turned and her concerns- mostly regarding her dad and Carly.

"Okay," Carly agreed. "Okay, let's do it."

* * *

"Well?" Veridia asked, coming into the kitchen the moment Carly let.

"It's Carly," Rita admitted, "she said she got attacked by something that came from the water that Full Moon before all this began."

"This cannot go undealt with," Veridia said. "Every turn she will get more accustomed to her form and who knows how long before she stops hunting fish and dolphins and goes after Mermaids or even humans."

Carly had already taken down a tiger shark, Mermaids would be pretty close behind on her prey list this time.

"It will be dealt with, but this isn't like those girls in Wales," Rita warned. "When people go missing nowadays people look for them and they have a lot of resources. Carly can't just disappear."

There were times it scared her how determinedly single minded Veridia could be. Once Veridia decided what had to be done - that was it, there was no convincing her otherwise. Fortunately she'd spent a great deal of time over the years being the one to do just that.

Emotions don't work for situations like this. Land people were not Veridia's favourite and a rogue Siren was a threat, there was no denying that, but Rita wasn't about to let the Council agree to murdering a kid. Not if there was something she could do.

"The Full Moon will be here before we know it and we need to decide what to do sooner rather than later."

"We can secure her here next Full Moon," Rita said, "Carly's already agreed to it and that gets us another month before she turns again."

"Here?" Veridia questioned.

"In the pool. The sea entrance can be blocked off and then the door. She'll be trapped and can't hurt anyone."

"Those things are strong. Can it be safely secured?"

"Someone will need to watch it all night but it will hold." It might hold. She knew _how_ to make it hold but as a teacher she knew that knowing how to do something isn't the same as being able to do something.

"If you are certain it will work, you can have the next Full Moon. I can't give any longer, this needs to be dealt with. If it fails then, I cannot stop the Council making a decision and acting on it."

"Don't you have the final say?" The Head of the Council held the power, Veridia had the final decision in all matters.

"Not if it's a unanimous decision. I risk my position if I go against every other Mermaid."

"It will work. I promise." There was no doubt she could set it up, any Mermaid could draw up a sigil and move some water around. Sealing it off was a bit harder by any Mermaid with her power could do that. Holding it up was another story. Without a Moon Ring there was no guarantee it would hold.

"I just need a Moon Ring," Rita added. Nixie had her one, wherever Nixie was. The Pod had been back for months but Nixie and Lyla had yet to return.

"I'll see what I can do."

* * *

**One Month Later - The Day Before The Full Moon**

"Everyone ready for tomorrow?" Evie asked joining Carly at the counter with Zac and Cam, both stuffing their faces with burgers - fish for Zac and good old fashioned hamburger for Cam.

"What's happening tomorrow?" Cam looked up, mouth full of burger.

"Full Moon," Carly reminded him. She loved him, but he could be pretty forgetful at times. Usually at the worst times.

"Oh yeah," Cam nodded upwards, "you still staying at Santos' place?"

"We are," Carly confirmed. "Mimmi's agreed to stay with us too." She felt better knowing Mimmi would be there, felt less like gatecrashing someone else's house and more like an invited sleepover.

"Girls night is it?" Zac asked, "It's okay we know our place. Don't we Cam?"

"Not sure Rita would agree with having you two staying over," Evie pointed out. She had a point, Carly couldn't imagine anyone being happy with having both Zac and Cam staying over, let alone their school principal.

"I have to say I'm offended," Cam set down his burger with a pout and crossed his arms in mock anger. "We're your oldest and bestest friends and you're excluding us?"

"It's rude, is what it is Cam. Isn't it?" Zac asked, mirroring Cam's actions. Carly rolled her eyes and Evie lightly smacked the back of Zac's head just enough to slightly ruffle his hair.

"Exactly," Cam pouted even further. "I'm upset. You upset me. How are you going to fix this?"

"Fix what?" Mimmi joined in, coming up beside Evie in front of the counter.

"They're pretending to be upset that they're not invited to our 'sleepover.'" Carly rested her elbows on the counter.

"You can come if you want," Mimmi offered.

"Yay!" Cam cheered and went back to his burger.

"At least Mimmi's nice," Zac nodded to his sister and went back to finishing his own burger.

"Are you sure?" Evie asked, turning to Mimmi. "They're not really upset, they're just being dramatic. I'm sure they'd both be fine having their own 'boy's night in'."

"Hey!" Zac protested. His protests went ignored.

"Why not? More of us there in case something goes wrong," Mimmi said, completely unbothered by her brother's antics. If only Mimmi had grown up with them. She hadn't spent enough time around Zac just yet to realise just how annoying he could really be. She'd soon learn.

"I mean if it's okay with everyone, I'd feel better with more people," Carly said. Her voice was quieter than she intended but it was enough.

"I'll bring popcorn," Zac grinned.

**Notes for the Chapter:**

> Hope you all enjoyed this chapter, chapter 4 hopefully won't be too far behind but then I always say that...
> 
> Anyways, until next time!


	4. Chapter 4

**Notes for the Chapter:**

> Sorry for the delay, but I'm back with the next part!

**The Day Before The Full Moon**

"Tomorrow night must not fail," Veridia said, standing up to leave her seat at the table.

If Rita was a lesser person she might well have rolled her eyes. She was tired of this conversation. She'd heard nothing but the last few days and it was wearing her nerve thin. Veridia had gone a whole two minutes sitting in the dining area while Rita drank her tea without bringing it up. It had been a nice two minutes.

"It won't," Rita re-assured, each word as fake as the other. In truth she had her own worries about the upcoming Full Moon and her part in it. If she failed then she was responsible for a Siren being released and any subsequent damage.

"If it does, I can't stop the Council..."

"I know," Rita interjected before Veridia could continue. She knew well enough what would happen. "You don't need to remind me."

"Before I leave, I got you a Moon Ring," Veridia withdrew the ring from the pocket of her dress and held it out. Rita accepted the ring from her and slipped it straight on her finger. She had been expecting something more from that moment - Moon Rings were such an important thing to Mermaids - but there was nothing. This was a temporary measure only. This ring wasn't to be her's.

"Is everything prepared?" Veridia asked.

"The sigils are drawn," drawn out onto the stone in chalk, and carved into rock. Such simple markings that held so much power, "it's all ready."

"Good. The Council met this morning and came to a decision - I will stay and help manage tomorrow night."

That was a shock. The head of the Council and leader of the Pod doesn't just miss the Full Moon ceremony. It's such an ingrained part of their culture, no one just 'misses' a Full Moon. Even she had her own rituals for those nights.

"Really?" Rita questioned.

"This needs to work for the good of the Pod," Veridia said. "And I thought you'd appreciate some company aside from a group of teenagers."

The break in Veridia's facade brought a smile to Rita's face. Just an hour ago Mimmi had asked if Zac and Cam could join the group already consisting of Carly, Evie and Mimmi. Something about Carly feeling better with more support and Mimmi saying it would be okay. If it helped the girl then she was all for it, but the idea of having all those teenagers in her house and on a Full Moon? Wasn't the happiest thought. Even if it had been her suggestion in the first place.

"Your company would be most appreciated."

It would be nice. The company would be appreciated, as she said, and having someone else who could help handle anything that went wrong. It did however mean Veridia would know anything that went wrong. If Veridia wasn't there then issues could be covered up.

"I thought it would be."

"Don't flatter yourself."

* * *

**The Full Moon**

As the day began to draw to a close, Carly's stomach grew tighter and tighter. Every Full Moon since that thing attacked, weird shit happened, why would this one be different? At least her parents hadn't picked up on the fact that it was every Full Moon or they wouldn't have let her out the door. But then Evie called by so they probably would have. That girl could convince anyone of anything.

Evie opened the gate to Principal Santos' house and Carly closed it behind them. Whatever happened to night, at least Evie would be here. And Cam. And Zac. And Mimmi. And how ever many other Mermaids there would be.

Evie had told her about the Moon Spell, the gap in her memory, the loss of control and waking up in the morning with no idea what had happened. While it may not be Moon Spell causing her problems it was nice knowing she wasn't alone with that type of experience.

It was terrifying thinking about what could happen.

She'd turned to the internet and tried to find anything that could connect to what happened to her. The closest she got was Werewolf. Which, kinda did fit, but sea-style. Attacked by something on a Full Moon then every Full Moon afterwards things went weird.

There was one thing that sounded interesting, the summary had been in English, talking about three girls that were attacked over in Wales, but the first line of the article was Welsh and was annoyingly unavailable in Australia.

Evie had said she'd look it up on her laptop, something about a VPN and setting a different location. Didn't help the fact that she couldn't speak Welsh but there was google translate for that, as long as it made some sense.

Ondina opened the door to them before they reached it.

"Where have you been?" Ondina crossed her arms and glared. She did not look a happy Mermaid.

"We said five thirty," Evie looked at her watch, "it's five thirty."

"Zac and Cam have been here five minutes and I want to drown them both already. Control your boyfriends."

"Not our jobs," Evie smiled sweetly and Ondina responded by slamming the door shut.

Evie and Carly shared a look. This was why Ondina was difficult to like. She was too quick to act and didn't really care about other's feelings.

The door reopened and Mimmi ushered them inside with rushed apologies for Ondina.

Carly took one look at the clear sky before following Evie inside. The Moon would be up soon enough and then they would find out just what was going on.

* * *

Rita had watched the clock all night, waiting, just waiting for the final irrefutable proof that they had the right girl. She'd been doubting herself ever since she gave Carly's name to Veridia. Everything fit so well, it had to be Carly. But there was still that niggling doubt...

"It's about to start," Evie announced, setting her laptop to the side. She'd shown them all earlier in the evening this app she'd downloaded that showed the Moon's pattern from anywhere in the world. Ondina had scoffed and called it useless while Mimmi had insisted Evie show her every little part of it.

That had been back when they had all been treating this like any other normal teenager sleepover, or at least had been acting like it as far as she knew. She'd chosen to stay out of the way with Veridia until almost moonrise before joining everyone down in the grotto.

Rita caught Veridia's eye and found herself holding her breath. She'd sworn blind that tonight would work. It had to work. For everyone's sake.

"3, 2, 1 and moonrise," Evie counted down.

She felt the rise of the Moon, and she wasn't the only one.

Carly dropped to her knees screaming.

"Get her in the water."

Evie's laptop was shoved to the side as she rushed forward to support Carly, grabbing one of Carly's arms, Zac grabbed the other.

The Siren taking over Carly's mind did not appreciate that action as Carly twisted around and lashed out at Evie - new grown claws slashing Evie's face. Evie cried out and dropped Carly. Zac forced Carly's hands behind her back until Cam grabbed her, forcing the girl to stay on her feet.

Rita helped Evie back up to her feet.

"Let me see," Rita held Evie's face up. The cuts were deep, four of them right across her cheek, narrowly missing her eye. If a Siren attacking a land girl caused a transformation she dreaded to think what a Siren attacking a Mermaid would do.

"There's anti-toxin up in the alcove," Rita said to Veridia. Veridia nodded and took over Evie.

She caught up with Zac and Cam halfway down the stairs.

The beginnings of fins burst from Carly's skin, along her arm, her back, tearing her shirt at the back, the exposed skin turning grey. She was more Siren than girl now, the shrieks the screams were nothing a human could ever make.

Carly surged forward and broke loose of her restraint landing heavily on the sandstone floor. Her breathing came out harsh and ragged as she dragged herself over the floor and slipped headfirst into the water.

The Siren rose out of the water and shrieked before diving under. Her tail was shorter than that of the Mermaids and dark grey almost black with a fluke like a dolphins - except the long extended spike.

"She's going to get out!"

Rita held her arm out and twisted her hand, her power flowing out to solidify the water into gel at the entrance to the tunnel. She'd spent hours carving enhancing sigils to ensure this held.

The Siren's tail flashed below the surface. Rita guessed she had seconds until the Siren tried to escape. She'd be scanning the pool for easy prey before taking off into open ocean to hunt.

Rita made the same motion with her other hand, the one she wore the Moon Ring. She held it for a second to harden that gel to an unbreakable glass-like substance before making her hand into a fist. Her Moon Ring glowed softly then gave off a burst of light.

She dropped her arms and almost stumbled backwards. It worked. It had worked. And they were right about Carly.

"What did you do?" Cam asked. "What the fuck is going on?!"

"I blocked off the sea entrance."

Carly surfaced again snarling. Not Carly. That was not Carly. Her teeth were sharp and pointed like a shark's. Her eyes were an off black. Her skin grey. The Siren slipped back under, just below the surface and shot towards them

"Get back upstairs."

From what Carly had told her the Siren that attacked her had leapt from the water onto the dock. The little ledge in the pool, designed to be easier to get out of, would be nothing. It was worth noting it seemed that Sirens could also survive at least some time on land.

Zac and Cam both darted up the stairs, Rita behind them. She turned on the edge of the second step and held her hand up to the wall, tapping against the white chalk mark she'd drawn on. Three interlocking circles with a line through the middle

The sigil began pulsating blue light that spread outwards along a white chalk line going up to the ceiling, along and back down the wall on the other side and across the floor. The entire time she'd been drawing it on she'd been silently praying to anyone listening for no one to come in.

She was small, the ceiling was high and the stepladder was too low. Enough said.

The space between the lines began filling up with water, drawing any and all droplets from the air to create a barricade between them and the Siren. . Rita curled her fingers in and the water began to boil, clouding over as the water heated. With her other hand she pulled more water from the air into the water doorway and used the same gesture as before to 'cure' the water. The water solidified into a translucent shield blocking the pool from the corridor and masking the Siren's view of them. She used her Moon Ring once again on the hardened water. The entire thing rippled in blue light then stilled.

"How did you do that? I've never seen anyone do that … thing," Zac made the hand gesture.

"It's not a common power, especially not in the south."

Only one Moon Pool held these powers, the one on the Irish coast. She'd visited it a few times in the past but with no Pod left to guard it - they'd hid it. Unless you know where it was, it was impossible to find it.

"Is Carly going to be okay?" Cam asked.

Through the water shield Rita could just make out the Siren. She was at the surface swimming in circles, like a dolphin trapped in an enclosure. Okay was a relative term. She might wear herself out, but then she could just as easily injure herself trying to escape.

"She's survived three transformations already out in the open," Rita answered carefully. She couldn't tell anyone if Carly would be 'safe' or not. "She's safer in here. We'll see how she is in the morning."

"What happened to her?" Cam asked.

"What even is she?" Zac asked.

"She's a Siren."

* * *

If Evie was being honest, which she usually was, Veridia made her uneasy. She had her moments but the Council Mermaid was too icy and uptight for her to be comfortable around. She had handed Evie a wad of fabric and instructed her to hold it against her cheek to try and ease the bleeding.

"This will sting," Veridia warned.

Evie nodded. It already did. It hurt to speak and she wasn't sure her voice would work, even if she wanted it to. Carly… Her screams echoed through to the grotto from whatever the hell was happening to her.

Veridia placed a strip of sponge soaked in something green against the first cut on Evie's cheek. She grimaced in pain. The pain that was already there tripled.

When Veridia applied the - whatever it was - to the second cut Evie hissed.

On the third she cried out.

"The next one is going to hurt a lot more but this needs to be done now."

Evie just nodded as silent tears made their way down her face. The fourth time made her scream and her vision go black. Through the fading conscious Evie was vaguely aware of slumping forward and hitting the table.

* * *

The Siren circled the pool. It was small. It was sea water sure but there was no movement to it. Nothing moving at all. She scanned each edge, looking for anything. There was blood in the water but nothing there.

She darted to the surface and dove back under, thrashing her tail on the surface. She was hungry. She needed to eat. Her teeth hurt at the gums with desire to sink them into flesh. The last few nights had been bliss, free rein of the ocean to kill at will. Now she was stuck in this tiny pool.

She needed to get out. She shot towards the exit and threw herself in it. Whatever blocked her escape held strong. She set about it with her claws for them to uselessly scrape off the edge. She shrieked and slammed her fists against it. She drifted backwards and bashed her tail into the blockade with no result.

* * *

Cam watched through the barricade as Carly's tail fluked at the surface, the actions followed by a series of muted thuds. Carly. A Siren. His brain couldn't quite connect the two. What even was a Siren? That thing Carly changed into was not when he would call a Siren.

"What. The fuck?" Was all Cam could say.

"Siren?" Zac asked. "I thought Sirens were… not... that."

"How did this happen?" Cam asked. "Carly was normal. She's been normal her whole life." Carly was just a normal, human person, like he was. The two of them, and David, were the normal ones amongst all the fishchicks and Zac.

"She was attacked by a Siren, but how it made her turn - I have no idea."

Attacked? Carly had never told him about that. But then he'd never told her about what happened to him. When that thing that looked a lot like the Mermaid in the pool attacked him.

**One Month Ago**

Cam liked his sleep. Sleep and food were two of his biggest motivators. So why he was out on the beach well after sunset when he should be in his bed, was beyond him. Actually it wasn't. He was out because his useless little sister hadn't taken their (her) dog Fluffy out and Fluffy had used the rug as a bathroom because someone (his little sister) hadn't trained Fluffy to ask when he wanted out and then his older sister demanded he take the ridiculous ball of dog out a walk.

He didn't like Fluffy. He was too small and too fluffy. He shed everywhere and Cam was convinced he had begun to develop an allergy. Which was something that happened. According to google.

Cam had walked half of the beach already when Fluffy began barking and pulling to no avail. He was too small to shift Cam in the slightest.

"What the fuck is your problem?" Cam pulled back on the lead and Fluffy yapped louder.

"What?!" Cam looked up. There was a blonde girl on the beach ahead of him, quite a distance so as he couldn't see who. She stumbled into the surf and cried out, twisting like a fish pulled out onto land. The girl heaved herself up and threw herself forward into the waves and vanished.

"What the fuck?" Cam ran towards the sea where the girl went in, dragging Fluffy behind him until the dog's tiny brain realised what Cam was doing and ran happily alongside him.

"Hey! Anyone there?" Cam scanned the waves. A blonde head surfaced and disappeared, the girl not seeing him. Cam squinted his eyes to look closer but she was gone before he could see her face. It might just be the light but it looked a bit like Carly.

"Carly? Carly!" Why was Carly out here? If it was Carly.

Cam looked around the beach. Empty enough. He set Fluffy's lead down and set some small rocks on top of it.

"Stay."

Cam crossed the last of the sand and waded into the water. It was cool against his legs and even colder against his face as he dove under. Cam surfaced straight away and swam out a few strokes before shoving his head under and trying to see. The salt stung his eyes even after he resurfaced.

The girl had vanished. Cam swam out further and dove right under the way he'd seen the Mermaids do, kicking his feet up for good measure. Cam uprighted himself and looked around, treading water. A flash of gold caught his eyes. Cam twisted to the side only for something large to slam into his stomach shoving him backwards.

On instinct he tried to breathe in and the salt sea invaded his lungs. He clawed at the water and kicked the get to the surface. He saw a grey shape shoot towards him and his mind screamed shark. But since when did sharks have hair?

He was inches from the surface when the thing collided into him again, finger like appendages scrabbling against him. Cam kicked up, the force of the water slowing his motion making the effort useless. Cam thrashed out and his fist bounced off scaly skin. Mermaid skin, not shark skin. He'd touched sharks before, they didn't feel like this.

Cam twisted and kicked and flailed, all the while his lungs burning and fighting the urge to cough out the water in his lungs. He needed to breathe. He needed to breathe so badly.

As soon as it had appeared, the thing left. He saw grey and gold and that was it. Whatever it was, was not something he wanted to see again. Something else grabbed him and Cam twisted round the best he good to fight. He stopped when he saw Evie and let her guide him up to the surface.

Cam surfaced and coughed up a lungful of water while Evie rubbed his back, using her powers to help every drop of water out of his lungs.

"What was that?" Evie asked.

"No," Cam took in a fresh of pure air, "idea. Just came from nowhere. All I saw was grey."

"Let's get you back to shore. What are you even doing out here?"

"Walking the dog," Cam answered nonchalantly.

"There's no dog."

"Fuck."

* * *

"What's a Siren?" Zac asked, taking the words from Cam's mouth.

"They're another type of Mermaid," Rita answered. "They're… different, less human, more dangerous."

"All those dead things on the beaches?" Zac questioned. Cam had heard about all that. He'd even seen the dolphin the Marine Park guy took.

"A Siren."

"Carly?"

"Seems most likely."

Cam shifted his attention to the layer of solid water keeping them from Carly. Black eyes met his own. Carly was in the water, only her eyes and the top of her head visible above the surface. She slipped under the surface and thrashed up her tail.

**Notes for the Chapter:**

> Hope everyone enjoyed the latest chapter. There's going to be at least one more part yet, maybe more, we'll see.
> 
> Also for anyone interested there is now a H20/Mako Mermaids discord. There's a link floating around on tumblr, check out h20justaddmako for the post, or the link is also in my instagram bio (instagram - mako_and_tails_and_stuff) 
> 
> Until next time!

**Author's Note:**

> Hope you all enjoyed! 
> 
> This is going to be a multiple parter, minimum of two parts, and part two is not far behind. 
> 
> Also I'm only just watching Siren S3 now so no spoilers. 
> 
> Until next time.


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